Navajo lawmakers have rejected a settlement to recognize the tribe’s water rights from the Little Colorado River basin, likely sending the tribe and its Hopi neighbor back to court to resolve their claims.

The Tribal Council voted 15-6 against the settlement during a special session in Window Rock. The vote also puts a stop to legislation in Congress to move the settlement forward because it needed the blessing of both the Navajo and Hopi tribes.

Critics saw the settlement as an attack on their aboriginal rights and tilted toward corporate interests. They urged lawmakers to vote it down and continue fighting in court. A case in Apache County had been on hold while the tribes and 30 other entities worked out a settlement decades in the making. Aside from Zuni Pueblo, no other Arizona tribe has acquired rights to the Little Colorado River.

Under the settlement, the tribes would have waived further claims to the river basin if the federal government funded more than $300 million in groundwater delivery projects. Kyl had said the settlement would address the water needs of the reservations and provide certainty of the state’s water supply for off-reservation communities.

Tribes often trade what could be huge water claims for the promise of federal funding to deliver water to tribal communities. A few American Indian water rights cases have been resolved through litigation.

Navajo President Ben Shelly ultimately backed the settlement as a way to avoid protracted courtroom battle and guarantee water delivery to tribal communities. He and Tribal Council Speaker Johnny Naize held public hearings across the reservation and received hundreds of comments on the settlement.

Shelly said that he would look for other ways to bring water to the communities on the western side of the reservation.

Naize has said lawmakers weren’t willing to accept the settlement as is and had urged colleagues to table it for further discussion. He said he would advocate for an independent review of the settlement and renewed negotiations that would result in more favorable terms for the tribe, though it’s unclear whether the other parties would be willing to work toward another settlement.

“We will not be rushed into a settlement that a majority of our citizens are uncomfortable with,” said Naize, who voted in favor of it.

The Hopi Tribe took two separate votes on the matter – one to oppose Kyl’s legislation and the other to support the settlement.

Much of the opposition to the settlement came from a provision that would provide the Navajo Nation capital with water from the Colorado River if the tribe extends the lease for a coal-fired power plant and the waiver language. But the failure of the Navajo Nation to extend the lease would not have killed the settlement in its entirety.